Abstract
This paper tries to outline the relationship between Constantinople and Rome, between Greek East and Latin West in terms of political and church history since 324 until 1453 and delineate the causes and consequences of cardinal events that caused the gradual mutual estrangement and the formation of two specific civilization spheres. These two entities (of once united Roman Empire) were results of: the migration of barbarian nations between 4th and 7th century A.D. (German tribes, Slavs and Avars, Arabs); the iconoclasm and the Photian Schism, which broadened the differences between the Roman Catholic Church and the Eastern Orthodox Church; the Great Schism of 1054 and its consequences; the crusades, that strongly deepened mutual animosity between the Christian East and West, especially the sack of Constantinople in 1204 and subsequent establishing of the Latin Empire; the role of the Empire of Nicaea for the creation of a new Hellenic identity; a pro-union efforts and anti-union reaction of the Palaeologan period.